An airbag is inflated to protect a vehicle occupant in the event of a vehicle collision. The airbag, stored in a folded state within a vehicle instrument panel, is deployed and inflated in the interior of the vehicle. The inflated airbag restrains the vehicle occupant and reduces the potential for injury that may result from a vehicle collision.
The National Highway Traffic Safety Administration (NHTSA) performs vehicle crash tests and applies a five-star rating system to vehicles based on the results of the tests. Five stars are awarded for the highest performing crash tests based on NHTSA's rating system that uses a Combined Probability of Injury (CPI) metric. Results are published for the benefit of consumers as a New Car Assessment Program (NCAP) and the five star rating is highly desirable.
Many factors are relevant in achieving the target for a five-star rating, Neck Injury Criteria (Nij) being a significant one. A measurement, My, which is a force moment about the neck y-axis, and a force, Fz which is the neck tension or compression component are used to calculate Nij. Therefore, a goal in airbag design is to reduce My and Fz. A flat front panel utilized in a conventional passenger airbag loads the chin and forehead of a vehicle occupant which may result in a head movement that increases Nij.
There is a need for an airbag design that minimizes loading on the occupant's head and neck. Minimizing loading reduces My and Fz, thereby reducing Nij and CPI. A lower CPI represents a reduced probability of injury.